The present invention relates to the detection of the beginning and the end of hot rolled stock being moved and passing on a roller track of type that is used in a rolling mill, and including an adjusting zone of the mill; the mill generally being provided for rolling flat stock, such as skelp, strip, plates, or the like.
Rolling mills of the type to which the invention pertains, particularly mills for rolling single sheets or plates include numerous pieces of equipment such as rolling stools, water cooling equipment, straightening equipment, and devices for manipulating and handling the rolling stock, all of which being controlled in some form from the position the rolling stock assumes or positions passed through during the operation, to thereby turn the respective equipment on or off. For this, then, sensing devices are included in the roller and/or conveyor track which, for example, respond to the thermal radiation of the roller stock. Alternatively, light barriers are used in that the stock, when present, interrupts the light barrier, and when absent no such interruption occurs. Optical sensors of this type, i.e. radiation sensors generally, require in either case extensive servicing particularly cleaning, because of the rough environment in which they are supposed to work. In case of a large sheet and plate stock rolling plant, the facilities that require cleaning, seemingly a simple task, are, in fact, quite extensive. Herein then one has to consider that in some instances any measurement and particularly a presentabsent detection has to be carried out when the sheet stock is hot; in other instances the temperature is quite low which requires, in fact, a different kind of systems. That is to say one cannot assume that the monitoring equipment at large is basically of a uniform construction and configuration throughout.